Photographic focal-plane shutter.



PATENTED FEB. 17; 1903..-

L. BORS-UM. PHOTOGRAPHIG FOCAL PLANE SHUTTER;

APPLICATION FILED AFB. 25, 1902.

4 SHEETS-SHEET 1.

N0 MODEL.

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No. 720,659. PATENTE D FEB. 17, 1903. L. BORSUM.

PHOTOGRAPHIG FOCAL PLANE SHUTTER.

APPLIOATION FILED APR. 26, 1902.

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. v No. 720,659 PATENTED-FEB. 17, 1903.

L. BORSUM.

PHOTOGRAPHIG FOCAL PLANE SHUTTER.

AP PLIOATION FILED APR. 26, 1902. N0 MODEL. 4 SHEETS-SHEET 4.

UNITED STATES PATENT OFFICE.

LOUIS BORSUM, OF PLAINFIELD, NEWV JERSEY.

PHOTOGRAPHIC FOCAL-PLANE SHUTTER.

SPECIFICATION forming part of Letters Patent No. 720,659, dated February17, 1903.

Application filed April 25, 1902.

Serial No. 104,668. (No model.)

will...

To all whom, it may concern:

Be it known that I, LOUIS BORSUM, a citizen of the United States,residing in Plainfield, county of Union, State of New Jersey, haveinvented certain newand useful Improvements in Photographic Focal-PlaneShutters, of which the following is a specification.

The primary feature of this invention c0111; prises a novel means bywhich the slit or opening in the shutter may be adjusted by manipulatingan appropriate device located outside of the shutter-frame, andincidentally associated with such means is a scaleor index by which theoperator may determine the width of the shutter-slit. In connection withsuch a scale or indicator there is employed a similar indicator operatedby the winding of the spring-drum or lower shutter-roll, that indicatesthe number of turnings of the springdrum, and consequently the speed ofthe shutter. By means of the two indexes, one giving the dimensions ofthe slit and the other approximate speed of the shutter, the operator isinformed of all conditions requisite for any special exposure.

Theinvention further contemplates certain improvements in theshutter-frame or inclosing casing. Generally these improvementscontemplate that the frame will be made of two telescopic sections stuckup or otherwise suitably formed from sheet metal, aluminium beingpreferably employed on account of its lightness and the ease with whichit may be worked. These sections when combined may have chambers at thetop and bottom of appropriate dimensions for containing the rolls, andintermediate them is the opening for the exposure formed in acountersunk or depressed part lying between the two end chambers, andthe top and lower walls of which are formed by parts of the walls of theend chambers between which the plate-holder is fitted to slide.

Heretofore ways of adjusting a focal-plane shutter-slit from theexterior of the box or shutter frame have been proposed; but none ofthem, as far as is known, are constructed in accordance with thisinvention, the details of which are hereinafter described.

In the accompanying drawings, Figure 1 is an elevation looking at theside of the shutter-frame, having a countersunk portion to receive asuitable plate-holder; Fig.2, an elevation of the opposite side, withthe telescoping section of the frame on that side removed and showingthe upper shutter-roll partly in section; Fig. 3, a detail view of theupper shutter-roll and associated parts, partly in longitudinal section;Fig. 4, an end elevation of the right-hand side of Fig. 1, showing theparts in position for the shutter to be tripped; Fig. 5, a view of theupper. part of Fig. 4, showing the parts in position immediately afterthe shutter has been tripped; Fig. 6, an end elevation on the left-handside of Fig. 1; Fig. 7, a horizontal section on the line '7 7 of Figs. 1and 4, showing, however, only the two telescoping members of the shutterframe or casing; Fig. 8, a detail view showing a modification in theconstruction of the clutch contained within the upper shutter-roll. Fig.9 is a detail view showing the way in which the slit-adjusting tapes areapplied to the end bars of the two shutter-sections. Figs. 10 and 11show in perspective the two parts of the telescoping casing, and Fig. 12is a like view of the slide piece for receiving the plateholder, andFig. 13 is a perspective view showing these three parts assembled.

This invention while not confined to is particularly applicable tocameras wherein the image is focused by the aid of mirrors or reflectorsupon a surface observable by the operator-as, for instance, in what isknown as a reflex camera, wherein the image formed by the lenses isreceived by a mirror placed at an angle of forty-five degrees in frontof the shutter and is reflected upwardly upon a piece of ground glass.

The mere details of construction shown and hereinafter described are notessential elements of the invention in its broader aspect, since,obviously, they may be varied by those skilled in the art. Experiencehas, however, demonstrated that the construction disclosed is apractical and efficient one.

A is the ordinary spring-drum or lower roll, mounted in suitablebearings in the frame.

B is the upper roll, the shaft C of which is under certain conditionscapable of rotation independently of the roll. Within the roll B, whichis shown as a hollow cylinder, is secured one member, I), of a clutch.The other member, 0, of the clutch is attached to the shaft 0, which iscapable of endwise movement to the left, as viewed in Figs. 2 and 3, toseparate the two members of the clutch, which are normally urged intoengagement by a coiled spring 0, contained within the hollow roll. Theshaft has suitable hearings in the frame and extends loosely through themember I) of the clutch secured within the r011 To one end of the rollthere is secured a toothed or ratchet wheel B, and outside of the wheelis a grooved pulley D, fitted 011 the squared part c of the shaft.Outside of the casing or frame the shaft has fixed to it a ratchet-wheelc and on the end of the shaft is a thumb-piece or button C. On theshaft, at the other end of the roll, is another pulley E, fitted upon asquared portion 0 of the shaft. Obviously when the shaft is drawnoutwardly to the left, as seen in Fig. 3, the two members of the clutchare separated, and the shaft is then capable of rotation independentlyof the roll, and the pulleys D E of course rotate with it. When theshaft is released, the spring 0 returns it and again brings intoengagement the two members of the clutch.

X and Y, respectively, indicate the upper and lower curtains orshutter-sections, and as y are their end bars or slats. Cords or tapes.2, preferably the latter, are attached at their ends to the pulleys Dand E, respectively, and the opposite end of each is threaded, Figs. 2and 9, through a slot in the end of the slat y and is then attached tothe slat a; by threading it through a slot therein and stitching it. Ifthere is a proper tension on the springdrum A, obviously if the shaft 0is shifted endwise to separate the members of the clutch it, with thepulleys D and E, may be revolved to effect a variation of theshutter-slit. To indicate to the operator the slit adjustment that hasbeen made, the following plan may be adopted: On the shaft outside theframe is loosely applied a spurpinion F, having a hub constituting aclutch member f. On the end of the shaft is fixed an opposing clutchmemberf'. When the shaft is moved endwise to adjust the slit, these twoclutch members pass into engagement and the pinion F is rotated. Itgears with a toothed wheel G, the face of which contains a scale to beread in connection with a pointer g, mounted on the side of the frame.The gear F may be held in position by a forked plate G, embracing thehub f and attached to the spindle of the wheel G. A rockshaft H, mountedin a bearing in the frame adjacent the end of the roll to which thetoothed wheel 1) is applied, carries a pawl 71. on its inner end that bya spring H is normally held out of engagement with said wheel. To theouter end of the shaft is applied an arm I, adapted to engage aspring-latch I on the side of the casing. The tripping-latch is shown asa bellcrank lever, to which is applied a spring 2", and one arm, i, ofwhich is the tripping-pawl and the other, F, is acted upon by the pistonof the pneumatic cylinder L or otherwise. An arm h, extending from therock-shaft H, lies between the ratchet-wheel c and a pin or projection ton the tripping-pawl 2'. Normally the spring 2" urges the pawl t' intoengagement with the ratchet c In the position of the parts shown in Fig.4 the arm h lies across the outer face of the ratchet-wheel c andprevents endwise movement of the shaft 0 when the curtain is being woundupon the upper roll. This is not of great importance when the spring 0is employed. To adjust the shutter-slit, the arm I is pulled down untilcaught by the latch I, when the pawl h will engage the toothed wheel 13and lock the roll. At the same time the armih moves the trippingpawl t'out of engagement with the ratchet-wheel on the roll-shaft G. If now theshaft 0 be moved endwise to the left, the adjustment of the slithereinbefore described may be made by rotating the shaft and with it thepulleys D E, the roll B being held positively against rotation. WVhenthe shaft 0 is returned to normal position by pressure or reaction ofspring 0, the spring-latch I may be pressed out of engagement with thearm I and all the parts will return to the normal position, (shown inFig. 4,) in which the shutter may be fully Wound on the roll B byrotation of the thumb-piece 0. To trip the shutter, it is only necessaryto throw up the arm F. The specific details of this part of thestructure of course are quite immaterial, as they may be varied in anyappropriate manner to suit any desired conditions or operations. Theshutter may be conveniently tripped by means of the pneumatlo cylinderL, to which is applied a tube L, having a bulb L and the plunger M ofwhich works against the arm 2' of the tripping pawl or latch.

On the same side of the casing as the shutter-slit index G a pinion O isapplied to the end of the shaft or spindle A of the springroll. Itmeshes with a gear-wheel O, mounted on the side of the casing andcarrying a pin 0, that once in each revolution advances a wheel 0 onestep or tooth. Suitable marks on the face of the wheel 0 read inrelation to a pointer 0 will indicate the number of turns given to aspring-roll, and consequently the approximate speed of the shutter.

If the tapes .2 are of the same thickness as the curtain and thewinding-roll B and pulleys D E of equal diameter, the slit-opening, whenof a certain width, will not be varied by the winding or unwinding ofthe curtain; but if the tapes are of greater or less thickness than thecurtain obviously the width of such slit-opening will change in passingin front of the plate. The general arrangement shown, in which tapes areemployed that are wound upon themselves in the same way that the curtainis, presents, therefore, the opportunity of controlling to a measurableextent variation of slit-opening in transit across the plate merely byusing tapesof a proper thickness as compared with the curtain. Forinstance, in this way the width of the slit may be decreased as itpasses the plate, thereby affording a longer exposure for theforegroundt'. e'., for the lower part of the plate.

The construction of easing or frame inclosing the shutter constitutes afeature of this invention, and the special form in which it is shown isas follows: A rectangular openfaced box or casing-section P is formed atthe top and bottom with rearwardly-extending projections P, formingenlarged or, as shown, substantially rectangular chambers, within whichrespectively the upper and lower rolls are mounted to rotate, theirrespective shafts being provided with hearings in the sides. Between thepart P P this member of the casing is of considerably less thickness.The depressed or countersunk face of this section is cut away to form arectangular openingp of appropriate dimensions relatively to the shutterand plate to be used. Within this opening is seated an open or skeletonrectangular frame Q, having a preferably continuous inwardly-projectingflange q, that passes into the opening to serve as a light-guard toprevent vagrant or reflected rays of light from reaching the platearound the edges of the shutter. On the outer side the flat portion q ofthis skeleton frame lies flat against the depressed face surrounding theopening 1) of the casing-section P. Around three sides of the fiat partq of the skeleton frame there is a raised curb or flange g oppositeparts of which fit close against the walls of the parts P P. The outeredges g of this curb are turned inwardly to form guides or ways for thereception of a plate-holder (not shown) of any appropriate construction.The plate holder may slide entirely below the flange or overturned edgesor its edges may be provided with grooves within which the flanges gfit. The plate-holder may be slid in from the open side which in thisinstance is the same side of the frame at which the tripping deviceshereinhefore described are located. A spring-latch Q, Fig. 1, will serveto retain the plate-holder in place. The raised edge or shoulder gformed by the flat part q of the skeleton frame at the open side, mayabut against a rib or shoulder that may be formed on the plate-holder,thus forming a joint that will insure exclusion of light. The othermember R of the frame or casing fits into the open face of the member P,and its side walls 1" may be of such depth as to conform to the sidewalls of the member P. At the corner where the ratchet-wheel B islocated the side wall of the part B is slotted or cut away, as indicatedby the dotted lines 7', Figs. 4 and 5, and as clearly shown in Fig. 10,so as not to interfere with the rock-shaft H, its pawl, &c.; but, asshown by the dotted line 1' in Fig. 5 and as is obvious from Figs. 10and 11, the wall of the member R at this point passes between the pulleyD and the wall of the member or box 1?, so as to hold the pulley inposition. At the other three corners of the member R its side walls areformed with slots r which straddle the two ends of the shaft A and theend of the shaft 0 at which the pulley E is located. The rolls andpulleys are therefore held in proper position. The back of the member Ris of course formed with a rectangular opening R to afford the properexposure. The two members P and R of the shutter frame or casing, aswell as the member Q, may each be struck up or formed from a singlepiece of sheet metal, and the whole structure is compact, light, and ofsmall dimensions. Where the adjustment described is to be made from theoutside of the camera-box, the shaft 0 may of course ,be sufficientlyprolonged and the button 0' placed outside of the box, or so that whenin normal position the button will lie in a recess or countersink in thewall of the box. The thumb-button of the springroll may also have, as isusual, endwise movement and may normally lie seated in a countersink ina wall in the camera-box, and of course the indicating devices, both asto width of the shutter-- slit and the tension of the spring-roll, mayall be located on the outer face of the camerabox.

In Fig. 8 is shown a modified style of clutch to be contained within theupper or winding roll. The central part of the shaft is squared, as ats, and slides within a correspondinglyshaped opening in a diaphragm s inthe roll. When the shaft is withdrawn endwise to sepa rate the clutchmembers, the squared part 8 passes out of engagement with therectangular opening in the partition.

S S are plates applied to the ends of the parts P P to afiord bearingsfor the indicatorwheels, the. They need not, of course, be used when thepart P is made of metal of sufficient thickness and strength to afiordproper support for such parts.

- I claim as my invention- 1. In a focal-plane shutter, the combinationof the shutter-sections, the spring-roll, the winding-roll and itsshaft, a clutch by which the winding-roll and its shaft may be locked torotate together or independent rotation of the shaft permitted,pulleysmounted upon the shaft to always rotate with it, and a flexibleconnection extending from each pulley to the lower shutter-section andthence to the upper shutter-section to which it is attached for thepurpose set forth.

2. In a focal-plane shutter, the combination of the shutter-sections,the spring-roll, the winding-roll and its shaft, a clutch by which thewinding-roll and its shaft may be locked to rotate together orindependent rotation of the shaft permitted, pulleys mount-ed upon theshaft to always rotate with it, and a flexible connection extending fromeach pulley to the lower shutter-section and thence to the uppershutter-section to which it is attached, whereby the shutterslit may beadjusted, and indicating devices for indicating to the op erator theadjustment of the shutter-slit.

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3. In a focal-plane shutter, the combination of the shutter-sections,the spring-roll and indicator operating on the winding of the roll toadvise the operator of the tension thereof, the winding-roll, means foradjusting the width of the shutter-slit, and indicating devices showingthe adjustment.

4. In afocal-plane shutter,the combination of the shutter-sections, thewinding-roll, its endwise-movable shaft, pulleys on the shaft at eachend of the roll through which the shaft slides, but which rotate withit, a clutch member attached to the roll within it and a second clutchmember movable within the roll and attached to the endwise-movableshaft, and flexible connections extending from each pulley through thelower shuttersection and thence to the upper shutter-section to whichthey are attached.

5. In a focal-plane shutter,the combination of the shutter-sections, thespring-roll, the winding-roll, a toothed wheel fast with thewinding-roll, the winding-roll shaft movable endwise within the roll, aclutch having one member rotating with the roll and another memberrotating with the shaft, a toothed wheel fast upon the roll-shaft,pulleys on each side of the winding-roll through which the shaft slipsendwise, but which rotate with it, flexible connections extending fromthe pulleys to the lower shuttersection and thence to the uppershutter-section to which they are attached, a tripping-pawl normallyengaging the wheel on the roll-shaft, a detent normally disengaged fromthe toothed wheel on the winding-roll, and means whereby when theroll-shaft is moved endwise for the adjustment of the shutter-slit thetripping-pawl is moved out of engagement with the wheel on theroll-shaft, and the detent engaged with the wheel on the winding-roll.

6. In a focal-plane shutter, means for adjusting the shutter-slitcomprising a hollow winding-roll, its shaft, a normally closed clutchlocking the shaft and roll to rotate together, means for opening theclutch to permit rotation of the shaft independently of the roll andpulleys mounted upon the shaft and always rotating with it.

7. In a focal-plane shutter, means for adjusting the shutter-slitcomprising a hollow winding-roll, its shaft, a normally closed clutchlocking the shaft and roll to rotate together, means for opening theclutch to permit rotation of the shaft independently of the roll,pulleys mounted upon the shaft and always rotating with it and means forlocking the roll when the shaft and pulleys are independently rotated.

8. In a focal-plane shutter, means for adjusting the shutter-slitcomprising the winding-roll, its shaft normally rotating with the roll,but capable of independent rotation when moved endwise relatively to theroll, pulleys mounted upon the shaft and always rotating with it, anindex for indicating the adjustment of the shutter-slit and a clutch bywhich the scale is operated each time that the shaft is moved endwise toadjust the slit.

9. In a focal-plane shutter the combination with the two rolls, theendwise-movable shaft of one of the rolls, a clutch interposed directlybetween the shaft and its roll and comprising two members one carried bythe rolls and the other by the shaft whereby the roll and shaft may belocked to rotate together or the shaft permitted to rotate independentlyof the roll, pulleys, at the ends of the roll, mounted on the shaft toalways rotate with it, and flexible connections extending as describedfrom the pulleys to the ends of the shutter-sections.

10. In a focal-plane shutter, the combination of the two rolls, pulleyslocated at the end of one of the rolls, means whereby said roll and thepulleys are locked to rotate together or the pulleys permitted to rotateindependently of the rolls, means for so independently rotating them andflat tape connections extending from the rolls to the ends of theshutter-sections as described.

11. In a focal-plane shutter, a frame comprising two telescopingsections each made of sheet metal and one of which is formed withprojections from one side thereof at the top and bottom forming chambersto receive the shutter-rolls, the space between the adjacent walls ofthese two enlargements being adapted to receive a plate-holder.

12. In a focal-plane shutter, a frame comprising two telescopingsections, one P, with the enlarged chambers P, P, for the reception ofthe shutter-rolls, and the other R, fitting within it as described, askeleton frame fitting within the exposure-opening of the first-namedframe-section, having a lightguard flange extending into the opening,and formed outside of the opening as a slide or way for the reception ofa plate-holder.

13. A focal-plane shutter -frame comprising opposite telescopingsheet-metal sections within which the curtains and rolls are contained.

In testimony whereof I have hereunto subscribed my name.

LOUIS BORSUM.

Witnesses:

KATHARINE MACMAI-ION, LILLIE F. BROWNING.

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